Long-term performance of activated carbon air cathodes with different diffusion layer porosities in microbial fuel cells

Type
Article

Authors
Zhang, Fang
Pant, Deepak
Logan, Bruce E.

KAUST Grant Number
KUS-I1-003-13

Date
2011-08

Abstract
Activated carbon (AC) air-cathodes are inexpensive and useful alternatives to Pt-catalyzed electrodes in microbial fuel cells (MFCs), but information is needed on their long-term stability for oxygen reduction. AC cathodes were constructed with diffusion layers (DLs) with two different porosities (30% and 70%) to evaluate the effects of increased oxygen transfer on power. The 70% DL cathode initially produced a maximum power density of 1214±123mW/m 2 (cathode projected surface area; 35±4W/m 3 based on liquid volume), but it decreased by 40% after 1 year to 734±18mW/m 2. The 30% DL cathode initially produced less power than the 70% DL cathode, but it only decreased by 22% after 1 year (from 1014±2mW/m 2 to 789±68mW/m 2). Electrochemical tests were used to examine the reasons for the degraded performance. Diffusion resistance in the cathode was found to be the primary component of the internal resistance, and it increased over time. Replacing the cathode after 1 year completely restored the original power densities. These results suggest that the degradation in cathode performance was due to clogging of the AC micropores. These findings show that AC is a cost-effective material for oxygen reduction that can still produce ~750mW/m 2 after 1 year. © 2011 Elsevier B.V.

Citation
Zhang F, Pant D, Logan BE (2011) Long-term performance of activated carbon air cathodes with different diffusion layer porosities in microbial fuel cells. Biosensors and Bioelectronics. Available: http://dx.doi.org/10.1016/j.bios.2011.08.025.

Acknowledgements
The authors thank D.W. Jones for helping with the analytical measurements, and Dr. Justin C. Tokash for helping with EIS data analysis. This research was supported by Award KUS-I1-003-13 from the King Abdullah University of Science and Technology (KAUST).

Publisher
Elsevier BV

Journal
Biosensors and Bioelectronics

DOI
10.1016/j.bios.2011.08.025

PubMed ID
21937216

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